/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.tudarmstadt.ukp.dkpro.bigdata.collocations;

import java.io.IOException;

import org.apache.hadoop.mapreduce.Reducer;

;

/** Combiner for pass1 of the CollocationDriver. Combines frequencies for values for the same key */
public class CollocCombiner
    extends Reducer<GramKey, Gram, GramKey, Gram>
{

    @Override
    protected void reduce(GramKey key, Iterable<Gram> values, Context context)
        throws IOException, InterruptedException
    {

        int freq = 0;
        Gram value = null;

        // accumulate frequencies from values, preserve the last value
        // to write to the context.
        for (Gram value1 : values) {
            value = value1;
            freq += value.getFrequency();
        }

        if (value != null) {
            value.setFrequency(freq);
            context.write(key, value);
        }
    }

}
